You can use more than one sound variation at a time, even though they may not appear in variations bar. For example, here is a screenshot of two variations being used at the same time: "Long Pad" and "Glissando.FX".
Simply select the notes in the editor you want to use the different sound variation, right click on them, and choose "Apply Sound Variation"...in this case the "Long Pad" on just the one note (G3), the short notes (C4,D4,E4) use "Glissando FX".
If you don't see the sound variations in the menu, you may need to configure the sound variation in the left hand side of the editor menu (see below). Click the wrench icon next to "Sound Variation", and then choose the matching variations in the popup dialog.
